It is currently the state of the art that enclosures for electrical circuits are made from precision shaped metal blocks. This shaping is however at a cost since it must be effected by expensive processes such as with milling/machining to achieve dimensional precision. Since the enclosures must be made with such high dimensional precision they require close tolerances in construction, and this is presently available only with milling/machining shaping processes. In addition, the metals used are limited since they must have coefficients of expansion which match the contained circuits since even slight deviations can adversely affect electrical connections performance. Accordingly, it has been the practice to form electrical enclosures from unitary metallic elements such as from blocks of KOVAR.RTM. alloy or other metal matched to the coefficient of expansion of the electronic or electrical element to be retained therein. In addition the enclosure wells are precisely milled/machined out of a metal (e.g., KOVAR slug or blank to provide a snug fit for the component to be contained therein.
While effective, milling or machining are relatively slow and expensive processes, even when utilized on a mass production basis, and especially if the production entails shaping changes in depth and configuration, as is often the case.
Simple and inexpensive metal forming processes, amenable to production line utilization, such as coining and stamping, because of the metal stretching involved, are inaccurate and susceptible to formation of unwanted holes in the stretched metal. Accordingly, use of such processes has not even been contemplated, except possibly for the formation of very simple enclosures not requiring a great degree of accuracy in the dimensions thereof.